The invention relates in general to measurements of flowing water, such as rivers and streams, and in particular to depth-integrating sampling and the measurement of water velocity.
In performing depth-integrating sampling, large samplers weighing upwards to 135 lbs. are used to perform sampling of suspended sediment. This is done by attaching the sampler to a reel system (typically a United States Geological Survey B-56 or E-53 reel) and mounting the reel system to a truck or reel crane. The sampler is attached to the cable on the reel and manually deployed carefully to the surface of the water. Because the sampler requires a precise speed through the water column, a metronome or audio type sounding device is used to compare an elapsed time with the payout and retrieval rate of the cable from the reel. A mechanical brake held by the operator is often used to accomplish this task. However, such an operation is very imprecise and inaccurate often times resulting in the sampling bag being overfilled or under filled.
For most applications, the operator is required to hand-crank the sampler when retrieving. For deploying the sampler, the operator uses the reel brake to control the speed of the sampler as it moves through the water column to the specified depth. The speed of the sampler is determined by a fraction of the mean velocity of flow. Higher stream flow velocities require faster deploying and retrieval rates for the sampler. In many instances, the sampler is only deployed to a fraction of the total depth due to the physical demands during retrieval and the ability of the operator to accurately time the sampler in the water.
In another application, instruments for measuring water velocity at specific depths are used to determine a mean velocity of flow. To perform this operation, the instrument, depending on the total depth of the water, is attached to a sounding weight and lowered all the way to the bottom to determine depth. The instrument is then brought to the surface and a mechanical measuring dial on the reel is used to determine the total depth. The indicator is then reset and the instrument lowered to a predetermined depth position in the water column to make the measurement. Such an operation requires not less than two personnel to perform due to one person designated to operate the reel and brake and the other person observing the position of the water-measuring instrument.
Although this activity appears coordinated, the operation becomes intense due to the precise control of the reel and observation of the position being observed from the bridge or platform. In most cases, the positioning is imprecise. In some cases, the operation can become very hazardous due to instrument deployment on a cablecar system where only a single person is positioned in a cablecar and the cablecar deployed across the river. This activity can be risky due to logistical movement and deployment of the sampler or instrument from the cablecar. Hand cranking the reel is still required to retrieve the instrument.
Depth-integrating samplers and instruments for measuring water velocity and water quality parameters are in continuous development and improvement. Although these instruments have emerged with greater range and depth capability, the methods to deploy these systems have not followed suit. In particular, a new sampler capable of greater speed and depth capability has completed development but weighs nearly 300 lbs. Such a sampler cannot be deployed using present methods and techniques. The physical and strength requirements to deploy such an instrument are not practical and as a result have necessitated the development of a motor control system capable of controlled speed and rates to be fully usable for this application. There is no commercially available motor control system in the open market that can satisfy the operating requirements for this newly developed sampler. Without the development of the motor control system, the sampler cannot be used and measuring capabilities would be set back and limited to less capable samplers.
A prior art apparatus for improving these methods uses a DC motor attached to the reel or truck. The motor is unidirectional, meaning the motor can only be operated in one direction. Also, there is no present method or capability to control the speed or provide for any type of variable speed operation. Finally, no other ancillary information such as actual motor speed or line payout length is provided that can improve operating conditions. This lack of information can be an extreme hazard to the operator due to high rotating speeds when the motor becomes engaged and can damage instruments due to excessive speeds and torque applied. This jerking and stress also causes premature failure in the cable and total loss of the instrument package.
The only other method for use under these conditions is a larger and more complex hydraulic system used to control speed. Such a system requires considerable maintenance. Also, the system is large and bulky, requires petroleum fuel to run, and no operator display information is provided. Finally, the system is very expensive and significantly more complex to operate. The inventor is aware of no other mechanical, electromechanical, or hydraulic deployment method to improve data collection and efficiency except that previously described.
The present invention relieves the operator of the physical demands to raise and lower the sampler or sounding weight because a bi-directional operating DC motor performs control of the reel and cable. Also, the operator is able to perform full control of the reel and motor using a remote controlled unit containing a visual display that provides important information such as actual motor speed; amount of cable payout or cable reeled in, battery voltage, and other information necessary to perform the operation in a safe and efficient manner. Additionally, because the operator may use a remote controlled unit, only a single person is needed to perform the measurement since the remote controlled device allows the user to be located where the instrument or sampler being used is in full view. The ability to turn on and off the motor and control the speed precisely can all be done using the hand-held remote control and display unit.
Such an operation is significantly less hazardous since the operator does not need to be where the reel is located thereby reducing exposure to fast moving parts and cable. The invention has a wide operating range allowing the operator to select and monitor precise speed both in instrument deployment and retrieval. The invention can maintain a constant speed of cable payout and retrieval regardless of the size weight attached. A simple and easy rotating dial is used to select a constant motor speed.
Thousands of sites throughout the United States and in other foreign countries are used to conduct water sampling and water stream flow measurements performed by the hundreds each month. Using present methods, the time to conduct measurements involves a substantial amount of man-hours and manpower. Often, field operations utilize three or more people and the physical demands require above average strength. Use of the present invention can significantly improve the number of measurements that can be made over the same amount of time and dramatically improve the precision and quality of the measurement. Additionally, a significant safety improvement is realized due to quicker operation in conducting the measurement thereby reducing the risk of injury when handling heavy equipment and reducing the need for physical strength required to perform the operation. The cost savings realized by improving the speed and accuracy of the measurement is significant.
Further objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.